carburater for 1970 40hp 40052A

[glenngraham]

I have a 40052a and trying to get a carburater kit for it but the one it calls for doesn't look like the one i have, I look at a 1971 40 hp and it looks like mine. There is a hole next to the top adjustment If I hold my finger over it runs a little better, like it is getting to much air but i'm not sure. I am new at working on boat motors and can us al the help i can get. The gas tank is band new but it swells up after setting in the sun i was thinking it should not swell if the vent is working ? Hope some one can help
Thanks

 

[F_R]

Re: carburater for 1970 40hp 40052A

Your motor should use 18-7024 carb kit. There will be extra parts in it so it will fit multiple models. Of course I suppose it is possible that somebody replaced the carburetor with a newer type. That would create a host of problems. The correct one for your motor has a hot-air heated automatic choke with electric booster. Does it?? It should have a steel hot air tube between the choke and exhaust cover.

That hole is the bowl vent. It must be open.

Gas tanks (new ones) often/usually have one-way vents to allow air to get in but not out. That is to prevent releasing vapors into the atmosphere in compliance with new environmental laws. Scarey, isn't it??? You can leave the cap loose, but don't tell anybody I said so.

 

[glenngraham]

Re: carburater for 1970 40hp 40052A

It doesn't have a tube running from exhaust but it has a electric choke and a manual choke. The carburater on mine has a adjustment on the top and one at the bottom off the bowl. The one it shows for mine only shows the adjustment on the top

 

[lindy46]

Re: carburater for 1970 40hp 40052A

Sounds like you may have an older carb on your motor, which actually would be good. The old ones without the automatic choke were a lot simpler in design and either the choke was on or off at the operator's discretion. Yours sounds like it has a high speed needle (lower one) and a slow speed needle, which are both adjustable. The newer ones had a fixed high speed jet. Can you post a picture?

 

[glenngraham]

Re: carburater for 1970 40hp 40052A

Yes I can, will post a picture tonight when i get home from work.

 

[F_R]

Re: carburater for 1970 40hp 40052A

1964 through 1970 had the hot air choke and one adjusting needle. 1971 had an electric choke solenoid mounted on the bottom of the carburetor, and two adjustment needles. It actually was a reincarnation of the 1957-58 carburetors. 1972 had the electric solenoid mounted on the side of the carburetor, and one needle.

The 1970 18-7024 carb kit can be used on all the other ones, except I'm not sure about the 1972. You will just have left-over parts which are not applicable.

Waiting for your picture.

EDIT: 1964-70 hot air choked carburetors required a different intake manifold and gasket. The gasket has four holes, the main big one, the two for the bolts, plus one for drawing air through the choke. If you bolt up a carburetor without the hot air choke, you will have an air leak through that extra hole unless you do something to block it off. That could be your running problem.

ALSO: If the hot air heater is still in the exhaust cover, no problem unless it is burned through. In that case, exhaust fumes will escape under the hood and the motor will run lousy. Also a fire hazard.

 

[glenngraham]

Re: carburater for 1970 40hp 40052A

Here are two pictures of my carb.

 

[glenngraham]

Re: carburater for 1970 40hp 40052A

Ijust check the extra hole for the hot air choke and look like it has been pluged off.

 

[lindy46]

Re: carburater for 1970 40hp 40052A

Use a Sierra 18-7010 carb kit for that carb. You're missing the high speed adjustment knob, which connects via a rod to that lower needle. Not a necessity, but makes adjusting high speed a little easier on the water.

 

[F_R]

Re: carburater for 1970 40hp 40052A

Yes, you won't be buying a bunch of extra parts if using the 7010. Same basic carb, different choke type

 

[glenngraham]

Re: carburater for 1970 40hp 40052A

Thanks for the help

 

[Blacksting]

Re: carburater for 1970 40hp 40052A

[

EDIT: 1964-70 hot air choked carburetors required a different intake manifold and gasket. The gasket has four holes, the main big one, the two for the bolts, plus one for drawing air through the choke. If you bolt up a carburetor without the hot air choke, you will have an air leak through that extra hole unless you do something to block it off. That could be your running problem.

ALSO: If the hot air heater is still in the exhaust cover, no problem unless it is burned through. In that case, exhaust fumes will escape under the hood and the motor will run lousy. Also a fire hazard.[/QUOTE]
I have a '66 RD28b and had a fire . i'm not in front of the motor now but will check those air hoses and holes youre talking about . i thought maybe it spit gas out and ignited on the selonoid ( hadnt found a place to mount this yet ) . then the fuel line melted and fell off feeding the fire almost out of control till i smothered it w/ a towel and garden hose . but i had the cover off , so my question is , can that carb release enough fumes to cause a fire w/o the cover ? if so what ignites it ? and what damage could the motor have besides wires ? it took about 3 or 4 minutes to put it out completely .

 

[glenngraham]

Re: carburater for 1970 40hp 40052A

Well i just took the boat back to see if i could get it running bettere but as i was going in foward gear it acted like it kicked out and the motor just tacked up i can lower the rpm and it will go slowly but when i give it gas it acts like its in neutral. Should i just start looking for a new motor? Could it be a hub or does it eve have a hub ?

 

[glenngraham]

Re: carburater for 1970 40hp 40052A

Need help

 

[tx1961whaler]

Re: carburater for 1970 40hp 40052A

Sounds like you have a spun prop hub. It will go slow, but it will slip if trying to go faster. You can check for this by using a marker to make a line across the back of the prop from the hub to the outside part of the prop. The prop is really two pieces; the inner hub and the outer prop and is pressed together with a rubber bushing in-between that you can't really see.

 

[glenngraham]

Re: carburater for 1970 40hp 40052A

The prop looks like it just has a pin though it and the shaft. Is the hub normally inside the prop?

 

[lindy46]

Re: carburater for 1970 40hp 40052A

You can't see the rubber hub, but it is in there. They can deteriorate with age, crack, shrink, etc. and must be replaced if they start slipping. About $40 to re-hub one at a prop shop or Johnnyrude dealer.

 

[glenngraham]

Re: carburater for 1970 40hp 40052A

Where is the hub located ?

 

[tx1961whaler]

Re: carburater for 1970 40hp 40052A

It is the center part of the prop.

 

[glenngraham]

Re: carburater for 1970 40hp 40052A

What is it mean non hud exhaust pin drive ?